on the Chemical Compounds of Azote and Oxtjgen, &c. 245 



No two of them agree, and he differs a little from them all : but 

 he takes care to adhere to the middle line of difference ; for any 

 person intimately acquainted with experimental chemistry will 

 readily perceive, in reading his Ncnv System of Philosophy, that 

 he is not an experimenter, notwithstanding what he asserts on 

 that subject : in short, whatever knowledge he possesses is evi- 

 dently derived from reading the experiments and the writings of 

 others. 



I will therefore pass over this contradictory detail, particularly 

 as it is almost in substance what Dr. Thomson advanced in his 

 History of theAtomicTheory in the Kncyclopcsdia Bnlannica,oi 

 which I have already taken notice in this Magazine for November 

 and December 1816. 



The only part of it that deserves any attention is what relates 

 to the doctrine of definite proportions, which Mr. Dalton at- 

 tempts to explain in his own way; but no mention is made oMts 

 original author. On this part he begins thus: " The subject of 

 the greatest difference amongst us is in regard to the absolute 

 weights of the elements azote and oxygen, which combine to 

 form the several compounds. Gay Lussac and most of the other 

 chemists I have mentioned, who follow him as volumists*, con- 

 tend that the proportions are as under: viz. 



]\f ensures. Measures. Measures. 



100 azote + 50 oxygen = 100 nitrous oxide. 

 100.... +100 .. .. =200 nitrous gas. 

 100 .... 4-150 .... = subnitrous acid. 



100.... +200 .... = 100 nitrous acid e as. 

 100.... +250 .... = nitric acid. " 



The foregoing proportions are pretty correct, as shall be shovvn 

 presently. 



" But (continues Mr. Dalton) from the views I entertain on 

 the subject as derived from experiments, the true portions of 



* My Comparntive View was published twenty years Ijcfore Mr. Daltoii's 

 New Si/stcm of Ptiilanophi/ anpeiired, and Guy Lussac liad wiitti;!) some 

 time after liiin. It will 1)6 fuund by any person who will take the pains of 

 carefully perusing my work, that 1 was perlcctly ac<i'jainted v, itii the pro- 

 portions in which {;ases combine in volumes; it was the jj;round-work, to- 

 i;ether with (heir specific gravities, on which my entire system rested: and 

 without this knowledge no human bein^ could attempt to estimate the dif- 

 ferent proportions in which they unite particle to particle; and much less 

 the relative size, aUd of course the relative weight, of those particles; for 

 the specific wei!;ht of the ultimate divisions of all kinds of ponderable 

 matter is the same— their size or diameter only constitutes the difference. 



Without a previous knowledj;e of the fore;;oin<; princij)lcs, we mi};ht as 

 well attempt to ascertain the weight of the most distant fixed stars, as those 

 of particles, atoms, or molecules of matter: hence it is evident th.U the 

 al;ove passage of his operates more against Mr. Dalton than any tiling that 

 could be brought for-^ard, 



Q 3 the 



